Apparatus and method of forming a compound structure

ABSTRACT

Compound structures and methods for forming the same are described. The compound structures can be used to form an enclosure. The enclosure may be formed from metal, such as aluminum, and further include one or more non-metal regions that allow for transmission and receipt of electromagnetic waves, such as radio frequency waves. The non-metal region can include a first section, a second section, and an optional cosmetic section. The first section can be firmly molded onto a metal section of the enclosure by small pores formed within the metal section. The second section can engage with interlock features of the first section. The optional cosmetic section can cover the first section and the second section such that the first section and the second section are not visible from an exterior of the enclosure.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority under 35 U.S.C § 119(e)to U.S. Provisional Application No. 62/156,143, entitled “APPARATUS ANDMETHOD OF FORMING A COMPOUND STRUCTURE,” filed on May 1, 2015, which isincorporated by reference herein in its entirety.

FIELD

The described embodiments relate generally to forming compoundstructures. In particular, the present embodiments relate to formingcompound structures that can be used with an enclosure used forelectronic devices. More specifically, a structure having a radiofrequency (RF) transparent section and an RF opaque section can beformed.

BACKGROUND

Many electronic devices include an antenna or multiple antennas capableof receiving and/or transmitting electromagnetic (“EM”) energy in theform of EM radio waves. Typically, the antenna(s) are enclosed within anenclosure that houses several other electronic components. In somecases, the enclosure is formed from a metal, such as aluminum oraluminum alloy, which can interfere with transmission and receipt of EMradio waves. In these cases, the enclosure may include a non-metalsection that allows EM radio waves to permeate through the enclosure.

It may be difficult, however, to attach a non-metal material to a metalmaterial with a strong enough bond to withstand some of the forcesexperienced by the electronic device. For example, if the bond is notstrong enough, a force created by a drop event can cause disengagementof the metal and non-metal portions. Adhesives can be used to helpsecure the metal and non-metal portions. However, even thin layers ofadhesive can be visible and detract from the aesthetic appeal of theenclosure. Fasteners, such as clip and screws, can be used to reinforcethe bond. However, fasteners can also be visible and unattractive, orthey can take up valuable space within the enclosure that can be usedfor internal components of the electronic device.

SUMMARY

This paper describes various embodiments that relate to formingenclosures for electronic devices that include radio frequency opaquesections, such as metal sections, and radio frequency transparentsections, such as plastic sections. The methods involve forming radiofrequency transparent structures that are strongly bonded to the metalsections and that provide improved radio transmission and/or cosmeticappeal compared to conventional methods.

According to one embodiment, a compound structure is described. Thecompound structure includes a first metal section having a recessdefining an interface surface. The interface surface has a pore with adiameter of less than one millimeter. The compound structure alsoincludes a second metal section. The compound structure further includesa radio-frequency (RF) transparent section including an RF transparentmaterial. The RF transparent section is engaged with the interfacesurface of the first metal section and wherein some of the RFtransparent material is positioned within the pore.

According to another embodiment, an enclosure is described. Theenclosure includes the enclosure having a first metal section and asecond metal section. The enclosure includes an RF transparent sectionsecuring the first metal section with the second metal section. The RFtransparent section is formed of an RF transparent material incorporatedwithin pores of at least one of the first metal section or the secondmetal section. The pores have diameters of less than one millimeter.

According to a further embodiment, a method of forming an enclosure foran electronic device is described. The enclosure includes a first metalsection and a second metal section. The method includes forming pores atan interface surface of the first metal section. The method alsoincludes molding a first RF transparent section on the interface surfacesuch that material of the first RF transparent section is molded withinthe pores. Molding the first RF transparent section includes forminginterlock features within the first RF transparent section. The methodfurther includes coupling the first metal section to the second metalsection by molding a second RF transparent section on the second metalsection and the first RF transparent section. The second RF transparentsection is molded within the interlock features of the first RFtransparent section.

These and other embodiments will be described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements.

FIG. 1 shows an electronic device including an enclosure, in accordancesome embodiments.

FIG. 2 shows a cross section view of a portion of the enclosure of FIG.1, in accordance with some embodiments.

FIGS. 3A-3C show a cross section views of a portion of the enclosure ofFIG. 1, in accordance with some other embodiments.

FIGS. 4A-4E show perspective views of the enclosure of FIG. 1 beingformed, in accordance with some embodiments.

FIG. 5 shows a flowchart indicting a process for forming an enclosure,in accordance with some embodiments.

Those skilled in the art will appreciate and understand that, accordingto common practice, various features of the drawings discussed below arenot necessarily drawn to scale, and that dimensions of various featuresand elements of the drawings may be expanded or reduced to more clearlyillustrate the embodiments of the present invention described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

Described herein are enclosures that can be used to house componentsthat transmit and/or receive electromagnetic waves (e.g., radiofrequency (RF) waves) for communications. The enclosures include RFopaque sections that generally do not allow transmission of RF waves toa sufficient degree for efficient communication. Such materials caninclude metal, which can provide a durability and aesthetic look andfeel to the enclosure. The enclosures also include RF transparentsections that generally allow sufficient transmission of RF waves forefficient communication. Such materials can include plastic, ceramic,glass and combinations thereof. The RF transparent section(s) can bepositioned proximate to antenna(s) housed within the enclosure that aredesigned to transmit and/or receive electromagnetic wave communications.

In a particular embodiment, the RF transparent section includes astructural RF transparent section, which can be made of a high strengthresinous material, and a mediating RF transparent section, which can actto increase a transmission region of the enclosure. The mediating RFtransparent section can be tightly secured to a first RF opaque section,and the structural RF transparent section can be tightly secured to asecond RF opaque section. The structural RF transparent section and themediating RF transparent section can interlock with each other using amolding process, thereby firmly coupling the first and second RF opaquesections of the enclosure. The RF transparent section can be in the formof a band that fills a gap between the RF opaque sections, creating anenclosure with a unique RF antenna region or gap that potentiallyincreases antenna performance.

One or both of the mediating RF transparent section and structural RFtransparent section can be interlocked with pore structures formedwithin the first and/or second RF opaque sections. The pores aregenerally very small, on a scale of micrometers or nanometers, providingample surface area for extra-tight adhesion between the RF transparentsection and the RF opaque sections. In some embodiments, the RFtransparent section includes a cosmetic RF transparent section thatcovers the structural RF transparent section and the mediating RFtransparent section, providing an aesthetically appealing exteriorsurface to the enclosure.

Methods described herein are well suited for providing cosmeticallyappealing structures for consumer products. For example, the methodsdescribed herein can be used to form cosmetically appealing housing orenclosures for mobile electronic devices, wearable electronic devices,portable computers, desktop computers, and electronic deviceaccessories, such as those manufactured by Apple Inc., based inCupertino, Calif.

These and other embodiments are discussed below with reference to FIGS.1-5. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes and should not be construed as limiting.

FIG. 1 shows a rear view of electronic device 100, in accordance withsome embodiments. In some embodiments, electronic device 100 is a mobilephone. In some embodiments, electronic device 100 is a tablet computingdevice. Electronic device 100 can include enclosure 102 that includes aninternal cavity (not shown) that is sized and shaped to house internalcomponents, such as one or more electromagnetic wave antennas (notshown). In some embodiments, the electromagnetic wave antenna(s)transmit and/or receive radio frequency (RF) wave communication, and canbe referred to as RF antenna(s). RF transmission refers generally to thetransmission of at least some frequencies within the RF spectrum. RFcommunication refers generally to communication using transmissionand/or receipt of at least some frequencies within the RF spectrum.Examples of RF communications can include Wi-Fi radio, Bluetooth radio,cellular radio, and/or NFC radio communications.

Enclosure 102 includes first metal section 104, second metal section106, and third metal section 108, which can be coupled by first RFtransparent region 110 and second RF transparent region 112. First RFtransparent region 110 and second RF transparent region 112 are RFtransparent such that one or more RF antennas housed within enclosure102 can receive or transmit RF communication through enclosure 102 viafirst RF transparent region 110 and second RF transparent region 112.First metal section 104 and third metal section 108 can be referred toas end pieces since they define ends of enclosure 102. Second metalsection 106 can be referred to as a chassis since it can defines mainside walls of enclosure 102. In some embodiments, first RF transparentregion 110 and second RF transparent region 112 can appear as thin bandsor lines that span a width of enclosure 102, and therefore can bereferred to as antenna bands or antenna lines. In some cases, first RFtransparent section 110 and second RF transparent region 112 arereferred to as splits or split regions of enclosure 102.

First metal section 104, second metal section 106, and third metalsection 108 are made of metal material(s), which generally do not allowelectromagnetic waves (e.g., RF waves) to pass through. First metalsection 104, second metal section 106, and third metal section 108 canbe made of any suitable metal or metals. In some embodiments, firstmetal section 104, second metal section 106, and third metal section 108are made of the same metal material to provide a continuous look andfeel to enclosure 102. In a particular embodiment, first metal section104, second metal section 106, and third metal section 108 are made ofan aluminum alloy.

First RF transparent region 110 and second RF transparent region 112 areat least partially made of an RF transparent material, which isgenerally a material that allows at least some of the frequencies withinthe RF spectrum to pass through. Suitable RF transparent materials caninclude resins (plastics), glass and/or ceramic. In some embodiments,first RF transparent region 110 and second RF transparent region 112 aremade of the same materials to give enclosure 102 a uniform look andfeel. In some embodiments, electronic device 100 includes a firstantenna positioned proximate to first RF transparent region 110 and asecond antenna positioned proximate to second RF transparent region 112,allowing efficient RF communication to and/or from electronic device100. In some embodiments, first metal section 104 and/or third metalsection 108 can act as part of the antenna(s) housed within enclosure102. Thus, one function of first RF transparent region 110 and second RFtransparent region 112 can be to electrically isolate and ground secondmetal section 106.

FIG. 2 shows a cross section view A-A of enclosure 102, in accordancewith some embodiments. As shown, RF transparent region 110 includes twosections: structural RF transparent section 202 and cosmetic RFtransparent section 204. Structural RF transparent section 202 providesstructural support for the coupling of first metal section 104 andsecond metal section 106, and therefore can be made of a stiff materialsuch as a stiff resin. Suitable polymer materials can includepolyarylether keytone (PAEK) materials (e.g., PEEK, PEK, PEKK) and/orpolysulfone materials (e.g., PSU, PPS, PES, PPSU, and PPS), and/orpolyester based materials (e.g., PBT, PET). Additionally, polymermaterials can also be blends and/or alloys of polymers previouslystated. In some embodiments, the resinous materials include fibers, suchas glass or ceramic fibers, to increase the strength of structural RFtransparent section 202. The composition of structural RF transparentsection 202 can also be chosen to be chemically resistant and retain itsgeometry when exposed to one or more additional processes subsequentmanufacturing processes. For example, resin(s) that do not substantiallydegrade or deform when exposed to an anodizing process can be used. Insome embodiments, the resin(s) do not substantially degrade or deformwhen exposed to ultraviolet (UV) light (e.g., by exposure to anultraviolet curing process), chemical coating, computer numericalcontrol (“CNC”) machining, blasting (e.g., sandblasting), and/orpolishing. Other factors in determining the material(s) used to formstructural RF transparent section 202 include strength sufficient towithstand impact during a drop event of enclosure 102, moldability ofthe material(s), and ability to form an external skin that is resistantto exposing internal portions of the polymer material.

Cosmetic RF transparent section 204 is situated such that a surface ofcosmetic RF transparent section 204 corresponds to exterior surface 201of enclosure 102. Thus, exterior surface 201 of enclosure 102 isdefined, in part, by surface portions of first metal section 104, secondmetal section 106 and cosmetic RF transparent section 204. Cosmetic RFtransparent section 204 can be made of the same material as structuralRF transparent section 202 or a different material. In some embodimentscosmetic RF transparent section 204 is made of a material that has morecosmetically or aesthetically appealing properties compared tostructural RF transparent section 202. Thus, cosmetic RF transparentsection 204 can be made of a different blend of polymer materials. Forexample, cosmetic RF transparent section 204 can be made of a uniform,color fade-resistant, and/or dent resistant material. Cosmetic RFtransparent section 204 can include a variety of colors, such as red,blue, green, black, white, or a combination thereof. Generally, thecolor or colors selected provides a desired aesthetic appearance. Insome embodiments, cosmetic RF transparent section 204 can also be madeof a material that is resistant to degradation and/or deformation whenexposed to one or more subsequent processes such as anodizing, UV lightexposure, chemical coating, CNC machining, blasting, and/or polishing.Suitable materials for cosmetic RF transparent section 204 can includeone or more suitable resinous, ceramic, and/or glass materials.

Cosmetic RF transparent section 204 can cover structural RF transparentsection 202 such that structural RF transparent section 202 is notvisible. That is, cosmetic RF transparent section 204 can preventstructural RF transparent section 202 from defining exterior surface 201of enclosure 102. The area of external surface 201 defined by cosmeticRF transparent section 204 can be a gap defined by length 211.

First metal section 104 of enclosure 102 includes extending portion 205,which can include interlocking feature 207 configured to interlock withcorresponding interlocking feature 208 of structural RF transparentsection 202. In some embodiments, structural RF transparent section 202is molded within enclosure 102 such that material of structural RFtransparent section 202 molds within and engages with interlockingfeature 207, forming corresponding interlocking feature 208.Interlocking features 207 and 208 can be any suitable combination ofprotrusions and recesses that increase the surface contact area of firstmetal section 104 and structural RF transparent section 202, therebyforming a stronger bond or adhesion between first metal section 104 andstructural RF transparent section 202. As shown, structural RFtransparent section 202 can include additional interlocking features 209and 210 that increase the adhesion to second metal section 106 andcosmetic RF transparent section 204, respectively.

Extending portion 205 can allow for good structural integrity andadhesion between first metal section 104 and structural RF transparentsection 202. However, the transmission of RF waves to and/or fromantenna 213 through RF transparent section 110 is limit by extendingportion 205. Specifically, extending portion 205 encroaches into the gapdefined by length 211 defined by cosmetic RF transparent section 204 andreduces RF transmission to a transmission region defined by length 212.The transmission region defined by length 212 corresponds to a pathwaywhere RF waves are free to pass. In a particular embodiment, length 211,which can correspond to a width of cosmetic RF transparent section 204,is about 2.0 mm and length 212 of the transmission region is about 0.6mm. To address the limitations that extending portion 205 places on theRF transmission capability of enclosure 102, modifications can be madeto the structure of enclosure 102.

FIG. 3A shows a cross section view A-A of enclosure 102, in accordancewith another embodiment. In this embodiment, RF transparent region 110includes three sections: mediating RF transparent section 214,structural RF transparent section 202 and cosmetic RF transparentsection 204. Mediating RF transparent section 214 can engage withinterface surface 203 of first metal section 104. Interface surface 203can be within a recess 103 of first metal section 104 to improveengagement between mediating RF transparent section 214 and first metalsection 104. Mediating RF transparent section 214 can include interlockfeatures 215 that engage with corresponding interlock feature 208 ofstructural RF transparent section 202. In this way, mediating RFtransparent section 214 can be referred to as an anchor. However, sincemediating RF transparent section 214 is RF transparent, this increasesthe area of a transmission region of enclosure 102. For example, thetransmission region can be a gap defined by length 211. In some cases,length 211 corresponds to a width of cosmetic RF transparent section204. In a particular embodiment, mediating RF transparent section 214increases the transmission region to a length 211 of about 2.0 mm. Thisincrease in the transmission region can correlate with increasedperformance of antenna 213. In some cases, the performance of antenna213 may be good enough that it may be desirable to shorten length 211 inorder reduce the relative area of cosmetic RF transparent section 204with respect to an exterior surface 201 of enclosure 102. For example,length 211 of cosmetic RF transparent section 204 could potentially bereduced to 0.6 mm. In this way, the addition of mediating RF transparentsection 214 can add a functional benefit of improved RF transmissioncapability and a cosmetic benefit of potentially smaller non-metalexterior surfaces of enclosure 102. This provides flexibility indesigning enclosure 102 while balancing and tuning function and cosmeticaspects.

As shown, mediating RF transparent section 214 is engaged with bothstructural RF transparent section 202 and cosmetic RF transparentsection 204. Cosmetic RF transparent section 204 can cover and preventstructural RF transparent section 202 and mediating RF transparentsection 214 from being visible. That is, cosmetic RF transparent section204 can prevent structural RF transparent section 202 and mediating RFtransparent section 214 from defining exterior surface 201 of enclosure102. This can be useful when mediating RF transparent section 214 and/orstructural RF transparent section 202 are made of material that does nothave a desirable aesthetic quality, such as a desired texture,consistency, color or hardness. However, in some embodiments, mediatingRF transparent section 214 and/or structural RF transparent section 202do have desirable aesthetic qualities. Therefore, cosmetic RFtransparent section 204 can be an optional member of RF transparentsection 110. In some embodiments, the interfaces between structural RFtransparent section 202, cosmetic RF transparent section 204, andmediating RF transparent section 214 can be enhanced by re-meltingduring injection molding processes. These aspects will be describedfurther below with reference to FIGS. 4A-4E.

In some embodiments, methods are employed to increase the adhesionstrength between mediating RF transparent section 214 and first metalsection 104. For example, first metal section 104 can be treated priorto molding of mediating RF transparent section 214 to increase thesurface area of an interface surface of first metal section 104. In aparticular embodiment, interface surface 203 of first metal section 104is chemically treated to create a porous interface surface. That is,interface surface 203 can be treated to create numerous small pores 216.The type of treatment will depend, in part, on the material of firstmetal section 104. Suitable chemical treatment for metals such asaluminum or aluminum alloys can include, for example, and acid etchingprocess. Pores 216 can be very small. For example, pores 216 can have anaverage diameter on a scale of micrometers (micro pores)—that is,smaller than one millimeter. In some embodiments, pores 216 have anaverage diameter on the scale of nanometers (nano pores)—that is,smaller than one micrometer. Once first metal section 104 is conditionedto have pores 216, mediating RF transparent section 214 can be moldedinto pores 216 to create a tightly knit bond between mediating RFtransparent section 214 and first metal section 104. Inset 218 shows aclose-up image of pores 216 with material of mediating RF transparentsection 214 formed therein. Since pores 216 are very small and thematerial of mediating RF transparent section 214 fills pores 216, atight mechanical interlock is created.

Since pores 216 are very small, it may be difficult to completely fillpores 216 with the material of mediating RF transparent section 214. Insome embodiments, flowable material of mediating RF transparent section214 (e.g., RF transparent in molten form) is molded on first metalsection 104 using a high pressure injection molding process such thatpores 216 are completely filled or nearly completely filled. Details ofsuch a high pressure injection molding process will be described belowfurther with reference to FIGS. 4A-4E.

FIG. 3B shows a cross section view A-A of enclosure 102, in accordancewith another embodiment. RF transparent region 110 includes threesections: mediating RF transparent section 214, structural RFtransparent section 202, and cosmetic RF transparent section 204.Mediating RF transparent section 214 can engage with interface surface203 of first metal section 104, with interface surface 203 positionedwithin recess 103 of first metal section 104 for improved engagement.Interface surface 103 can include small pores 216 (e.g., micro pores ornano pores) for further increased engagement between mediating RFtransparent section 214 and first metal section 104. Mediating RFtransparent section 214 can include interlock features 215 that engagewith corresponding interlock feature 208 of structural RF transparentsection 202. In the embodiment of FIG. 3B, interface surface 303 ofsecond metal section 106, formed within recess 105 of second metalsection 106, is also treated to have pores 302 (e.g., micro pores and/ornano pores). That is, first metal section 104 can have a first set ofpores 216 and second metal section 106 can have a second set of pores303. The material of structural RF transparent section 202 is moldedwithin pores 302 of second metal section 106.

FIG. 3C shows a cross section view A-A of enclosure 102, in accordancewith a further embodiment. In this embodiment, RF transparent region 110includes two sections: anchor or mediating RF transparent section 214and cosmetic RF transparent section 204. Mediating RF transparentsection 214 can secure first metal section 104 and second metal section106. Cosmetic RF transparent section 204 can cover mediating RFtransparent section 214. Mediating RF transparent section 214 can beformed of a flowable material (e.g., in molten form) incorporated withinpores 214 formed within recessed interface surface 203 of first metalsection 104 and pores 302 formed within recessed interface surface 303of second metal section 106. In other embodiments, only first metalsection 104 has pores 216 while second metal section 106 does not havepores 302. In yet other embodiments, second metal section 106 has pores302 while first metal section 104 does not have pores 302. That is, oneor both of first metal section 104 and second metal section 106 can havepores 216/302 capable of interlocking with RF transparent section 110that couples mechanically couples first metal section 104 and secondmetal section 106. In this way, radio frequency transparent anchor ormediation section 214 defines a radio frequency transmission region ofenclosure 102 that includes a gap defined by length 211 between thefirst metal section 104 and second metal section 106.

FIGS. 4A-4E show perspective views of enclosure 102 being formed usingprocesses in accordance with some embodiments. At FIG. 4A, first metalsection 104 of enclosure 102 is provided. At this point, first metalsection 104 can be in the form of a block or buck since one or moreshaping processes can be used to form a final shape of first metalsection 104. First metal section 104 can be made of any suitablematerial. In some embodiments, first metal section 104 is made of ametal material, such as aluminum or aluminum alloy.

At 4B, recess 103 is formed within first metal section 104. Recess 103can define an interface surface 408 for engaging with a molded pieceduring a subsequent molding process. In some embodiments, interfacesurface 408 is curved in accordance with a final exterior shape ofenclosure 102. Interface surface 408 can be formed using tool 406, whichcan be controlled by a machine, such as a CNC machine. In someembodiments, grooves 410 are formed within interface surface 408.Grooves 410 can define the portion of interface surface 408 that ismolded on during the subsequent molding process. The surface area ofinterface surface 408 can be increased by forming micro pores and/ornano pores at interface surface 408. In particular embodiments wherefirst metal section 104 is made of a metal, such as aluminum or aluminumalloy, micro pores and/or nano pores can be formed by an etchingprocess, such as an acid etching process.

At FIG. 4C, mediating RF transparent section 214 is molded on interfacesurface 408. That is, the material of RF transparent section 214 whilein a flowable state (such as in a molten form from heating) is injectionmolded onto interface surface 408. As shown, mediating RF transparentsection 214 protrudes from interface surface 408 and can have one ormore interlock features 215. In some embodiments, an injection moldingapparatus capable of injecting the flowable material under high pressuresuch that material of mediating RF transparent section 214 can be fullymolded within the pores of interface surface 408. In some embodiments,pressures in the range of about 30,000 psi are used, with increasingpacking pressure (e.g., 35,000 to 40,000 psi) applied as the pores fill.In some embodiments, the pressures are high enough to deform first metalsection 104. However, some deformation may be tolerated since firstmetal section 104 can undergo a post-injection molding shaping processin order to form a final shape.

The gates of the injection molding apparatus can be arrangedsubstantially orthogonal to interface surface 408, as indicated byarrows 412. As illustrated in inset 414 showing a cross section close upview at interface surface 408, pores 206 of first metal section aregenerally aligned orthogonal to interface surface 408. Thus, the flow412 of material orthogonal to interface surface 408 amounts tosubstantially parallel flow of material with respect to pores 206. Thistype of flow can further assure that pores 206 are sufficiently filledto provide extra strength adhesion between first metal section 104 andmediating RF transparent section 214. In this way, mediating RFtransparent section 214 adhered to first metal section 104 can bereferred to as a compound structure, with pores 206 acting as aninterlock feature of first metal section 104. It should be noted thatthis is contrary to conventional processes that would likely avoiddirect high pressure injection molding with orthogonal flow of materialrelative to interface surface 408 since such conditions may bend firstmetal section 104. In the methods described herein, however, somebending of first metal section 104 can be tolerated since first metalsection 104 can be shaped subsequent to the injection molding process.After the injection molding process is complete, one or more processescan be used to further shape mediating RF transparent section 214, suchas one or more machining, deburring or degating processes.

FIG. 4D shows first metal section 104 positioned next to second metalsection 106. As with first metal section 104, second metal section 106at this point can be in the form of a block since subsequent shaping cantake place. Structural RF transparent section 202 is then molded onsecond metal section 106 and mediating RF transparent section 214,thereby coupling first metal section 104 and second metal section 106.Structural RF transparent section 202 can engage with interlock features215 (shown in FIG. 4C) of mediating RF transparent section 214. In someembodiments, the molding process involves partially re-melting thematerial of mediating RF transparent section 214 such that structural RFtransparent section 202 is more firmly adhered to mediating RFtransparent section 214. For example, the molding process can bedesigned to locally liquefy mediating RF transparent section 214 atreinforcement/bonding points such that the material of structural RFtransparent section 202 partially intermingles with the material ofmediating RF transparent section 214 during the molding process. In someembodiments, the coupling of first metal section 104 and second metalsection 106 is enhanced using ultrasonic welding techniques, laserwelding techniques and/or use of adhesive(s).

At FIG. 4E, cosmetic RF transparent section 204 is molded on structuralRF transparent section 202 and mediating RF transparent section 214, andbetween first metal section 104 and second metal section 106. In someembodiments, the molding process involves a re-melting process, asdescribed above, that intermingle the material of cosmetic RFtransparent section 204 with the material of structural RF transparentsection 202 and/or mediating RF transparent section 214, thereby forminga stronger bond. In addition, first metal section 104 and second metalsection 106 are shaped to a final shape. The shaping and/or finishingprocesses can create a smooth and continuous exterior surface 201 ofenclosure 102. Any suitable shaping process and/or finishing process canbe used. For example, one or more machining (e.g., CNC), polishing,blasting and/or anodizing processes can be used. Note that the shapingprocess can compensate for some, if any, deformation of first metalsection 104 and/or second metal section 106 during previous moldingprocesses. An anodizing process can be used to anodize first metalsection 104 and second metal section 106. Thus, if cosmetic RFtransparent section 204, mediating RF transparent section 214 andstructural RF transparent section 202 are made of plastic material(s),the plastic material(s) should be resistant to substantial degradationwhen exposed to the anodizing process.

Referring back to FIG. 1, it should be noted that the processesdescribed above with respect to coupling first metal section 104, secondmetal section 106 with first RF transparent region 110 (includingstructural RF transparent section 202, mediating RF transparent section214, and cosmetic RF transparent section 204) can be used to couplethird metal section 108 with second metal section 106 using second RFtransparent region 112. That is, second RF transparent region 112 caninclude a corresponding structural RF transparent section, mediating RFtransparent section, and cosmetic RF transparent section that arearranged similarly to structural RF transparent section 202, mediatingRF transparent section 214, and cosmetic RF transparent section 204.

FIG. 5 shows flowchart 500 indicating a process for forming anenclosure, in accordance with some embodiments. At 502, a first metalsection of the enclosure is optionally shaped using one or more shapingprocesses. In some embodiments, the first metal section is made of analuminum alloy. The optional shaping process can involve creating ageneral shape that has dimensions roughly close to a final shape of thefirst metal section. In one embodiment, the shaping process includesforming recesses and engagement features within the first metal section.

At 504, small pores are formed within an interface surface of the firstmetal section. The pores can be micro pores, meaning an average diameterof the pores is on a scale of micrometers, and/or nano pores, meaning anaverage diameter of the pores is on a scale nanometers. The pore formingprocess will depend, in part, on the material of the first metalsection. In a particular embodiment where the first metal section ismade of aluminum or aluminum alloy, an acid etching process is used.

At 506, a first RF transparent section (e.g., mediating RF transparentsection 214) is molded on the interface surface of the first metalsection. Material of the first RF transparent section is molded withinthe pores of the first metal section. The material of the first RFtransparent section can be chosen such that optimal flow within thepores is achieved. In some embodiments, a high pressure injectionmolding process is used. Injection molding gates can be positioned toprovide substantially parallel flow of the material relative to thepores such that the pores are sufficiently filled to provide goodadhesion between the first RF transparent section and the first metalsection. In some embodiments, the first RF transparent section includesa fiber composite material having fibers within a resinous base. In someembodiments, the fibers are made of glass. During injection moldingprocess, fibers having small enough dimensions may fit within the pores,while fibers having larger dimensions do not fit within the pores. Insome embodiments, the average size of the fibers is chosen to be smallenough to fit within the pores. In any case, at least the resinous basematerial should be injectable within the pores.

In addition to choosing a material that provides good flow within thepores, the material of the first section can also be chosen to providesufficient re-melting during a subsequent molding processes for applyinga second RF transparent section and a third RF transparent section. Insome embodiments, one or more interlock features are formed on the firstRF transparent section, which is configured to interlock with asubsequently molded second RF transparent section. The interlockfeature(s) can include one or more protrusion and/or recesses.

At 508, a second RF transparent section (e.g., structural RF transparentsection 202) is molded on the first RF transparent section and a secondmetal section. In some embodiments, second RF transparent section ismade of the same material as the first RF transparent section. In otherembodiments, the second RF transparent section is made of a differentmaterial that the first RF transparent section, such as a stifferresinous material. In some embodiments, the molding process is designedto locally re-melt the material of the first RF transparent section suchthat a stronger bond is formed between the first RF transparent sectionand the second RF transparent section. If the first RF transparentsection has interlock features, the second RF transparent section can bemolded around and/or within the interlock features, formingcorresponding interlock features within the second RF transparentsection.

At 510, a third RF transparent section (e.g., cosmetic section RFtransparent section 204) is optionally molded on the first and second RFtransparent sections. The third RF transparent section can cover thefirst and second RF transparent sections such that the first RFtransparent section and the second RF transparent section do not form anexterior surface of the enclosure. This can be useful when the first andsecond RF transparent sections do not have desired cosmetic or aestheticproperties. For example, the first and second RF transparent sectionsmay have good structural integrity but do not have a desired continuousand uniform look and feel. Or the first and second RF transparentsections may not have a desired color and predetermined fade-resistance.In some embodiments, the first RF transparent section, the second RFtransparent section and the third RF transparent section are each freeof metal material in order to retain good RF transparent properties ofthe RF transparent region.

At 512, the enclosure is optionally shaped such that an exterior surfaceof the enclosure has a predetermined shape and/or smoothness. This caninvolve co-machining the first metal section, second metal section andthe third RF transparent section. In addition, the enclosure can befinished using one or more finishing processes such as polishing,blasting, buffing and/or anodizing. It should be noted that additionalmetal sections of the enclosure can be coupled using additional RFtransparent sections. The finished enclosure will have an RFtransmission region defined by the RF transparent section(s) and thatallows RF waves to pass through.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium for controlling manufacturing operations oras computer readable code on a computer readable medium for controllinga manufacturing line. The computer readable medium is any data storagedevice that can store data which can thereafter be read by a computersystem. Examples of the computer readable medium include read-onlymemory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, andoptical data storage devices. The computer readable medium can also bedistributed over network-coupled computer systems so that the computerreadable code is stored and executed in a distributed fashion.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not targeted to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

1. A compound structure comprising: a first metal section having arecess defining an interface surface, the interface surface having apore with a diameter of less than one millimeter; a second metalsection; and a radio-frequency (RF) transparent section including an RFtransparent material, wherein the RF transparent section is engaged withthe interface surface of the first metal section and wherein some of theRF transparent material is positioned within the pore.
 2. The compoundstructure of claim 1, wherein the second metal section includes a secondrecess defining a second interface surface having a second pore, whereinthe RF transparent section is engaged with the second interface surfaceof the second metal section and wherein some of the RF transparentmaterial is positioned within the second pore.
 3. The compound structureof claim 1, wherein the RF transparent section is a first RF transparentsection, wherein the compound structure includes a second RF transparentsection secured to the first RF transparent section, the second RFtransparent section engaged with the second metal section.
 4. Thecompound structure of claim 3, wherein the second RF transparent sectionis engaged with a second interface surface of the second metal section.5. The compound structure of claim 1, wherein the RF transparent sectionis composed of a fiber composite material including fibers within aresinous base.
 6. The compound structure of claim 1, wherein the porehas a diameter less than one micrometer.
 7. An enclosure for anelectronic device, the enclosure having a first metal section and asecond metal section, the enclosure comprising: a radio frequency (RF)transparent section securing the first metal section with the secondmetal section, the RF transparent section formed of an RF transparentmaterial incorporated within pores of at least one of the first metalsection or the second metal section, the pores having diameters of lessthan one millimeter.
 8. The enclosure of claim 7, wherein the firstmetal section includes a first set of pores and the second metal sectionincludes a second set of pores.
 9. The enclosure of claim 7, wherein theRF transparent section is a first RF transparent section, wherein theenclosure includes a second RF transparent section secured to the firstRF transparent section.
 10. The enclosure of claim 9, wherein the firstRF transparent section and the second RF transparent section includecorresponding interlock features interlocking the first RF transparentsection and the second RF transparent section.
 11. The enclosure ofclaim 9, wherein the first RF transparent section is composed of adifferent material than the second RF transparent section.
 12. Theenclosure of claim 10, wherein the second RF transparent section is madeof a more rigid material than the first RF transparent section.
 13. Theenclosure of claim 9, wherein the enclosure includes a third RFtransparent section that covers the first RF transparent section and thesecond RF transparent section.
 14. The enclosure of claim 7, wherein thethird RF transparent section forms an antenna band that fills a gapbetween the first metal section and the second metal section.
 15. Theenclosure of claim 7, wherein the pores have diameters less than onemicrometer.
 16. The enclosure of claim 7, wherein the RF transparentsection is composed of fibers within a resinous base.
 17. A method offorming an enclosure for an electronic device, the enclosure including afirst metal section and a second metal section, the method comprising:forming pores at an interface surface of the first metal section;molding a first RF transparent section on the interface surface suchthat material of the first RF transparent section is molded within thepores, wherein molding the first RF transparent section includes forminginterlock features within the first RF transparent section; and couplingthe first metal section to the second metal section by molding a secondRF transparent section on the second metal section and the first RFtransparent section, wherein the second RF transparent section is moldedwithin the interlock features of the first RF transparent section. 18.The method of claim 17, wherein the first RF transparent sectionincludes fibers within a resinous base.
 19. The method of claim 17,wherein molding the first RF transparent section on the interfacesurface of the first metal section comprises: injecting the material offirst RF transparent section while in a molten state in a directionsubstantially orthogonal to the interface surface.
 20. The method ofclaim 17, further comprising: molding a cosmetic RF transparent sectionof the RF transparent section on the first RF transparent section andthe second RF transparent section such that the cosmetic RF transparentsection covers the first RF transparent section and the second RFtransparent section.